var waveObj = function(){
    this.x = [];
    this.y = [];
    this.alive = [];
    this.r = [];
}
waveObj.prototype.num = 10;
waveObj.prototype.init = function(){
    for(var i = 0; i < this.num; i++){
        this.alive[i] = false;
        this.r[i] = 0;
    }
}
waveObj.prototype.draw = function(){
    for(var i = 0; i < this.num; i++){
        ctx1.save();
        ctx1.lineWidth = 2;
        ctx1.shadowBlur = 10;
        ctx1.shadowColor = "white";
        if(this.alive[i])
        {
            this.r[i] += deltaTime * 0.04;
            if(this.r[i] > 50){
                this.alive[i] = false;
                break;
            }
            var alpha = 1- this.r[i] / 50;
            //api
            ctx1.beginPath(); 
            ctx1.arc(this.x[i], this.y[i], this.r[i], 0, Math.PI * 2);
            ctx1.closePath();
            ctx1.strokeStyle = "rgba(255,255,255" + alpha + ")";
            ctx1.stroke();
            //draw
        }
        ctx1.restore();
    }
}
waveObj.prototype.born = function(x, y){
    for(var i = 0; i < this.num; i++){
        if(!this.alive[i])
        {
            this.alive[i] = true;//born
            this.r[i] = 10;
            this.x[i] = x;
            this.y[i] = y;
            return; 
        }
    }
}